Nonarcing switch



A ril 29, 1924.

H. H. CLARK NONARCING SWITCH 2 Sheets-Sheet 1 Filedf Dec. 4, 1919ATTORNEYS.

A ril 29, 1924.

H. H. CLARK V NONARCING SWITCH 2 Sheets-Sheet 2 Filed Dec. '4', 1919 BYt W ATTORNEYuS.

Patented Apr. 29, 1924.

UNITED STATES PATENT OFFICE.

noiuncme swrrcn.

Application filed December 4, 1919. Serial lo. 842,417.

To all whom it may concern:

Be it known that I, HAROLD H. CLARK, a citizen of the United States ofAmerica, residing at Springfield, in the county of e Hampden and Stateof Massachusetts, have invented certain new and useful Improvements inNonarcing Switches, of which the following is a speclfication.

This invention relates to improvements in non-arcing switches and, morearticularly,

to switches of this character which are suitable for use in localities,such as mines, where inflammable gases are prevalent, for breakingcircuits which carry relatively heavy currents. The invention aims torovide a switch which may be used with sa ety in such localities and, inpractical efiect, be explosion proof.

The broad object of this invention is to provide in a switch, means, inthe character of a liquid conductor, which, when the switch is closed,forms with the switch blade a divided circuit, and which when the switchis first opened carries all the current N fora momentary interval(thereby preventing an are between the blade and its'jaw) and laterbreaks the circuit out of contact with the surroundin atmosphere bydisplacement of the con uctor.

:0 Another object of the invention is to provide a switch, whichincludes a blade pivoted to swing from an upper and closed (position toa lower and open position an a chambered member carried by the bladeandcontaining a liquid conductor, such as mercury, which when the blade isin closed position forms with the blade a divided circuit, and when theblade is in open, but still in generally upri ht position, carries thecur- 4 rent until furt er fmovement toward its lower sition, wherein theliquid conductor is disp aced to break the circuit in the chamberedreceptacle.

Another object of the invention is to 1'0- 46 vide a single pole, doublebreak. switc of the pivote knife blade type, wherein the jaws areelectrically connected together and the blades carry a chambered membercon- -taining a liquid conductor, such as mercury,

which when the blades are in nerall upright position forms a shunt eectrica connection between the blades, such connection being broken bydisplacement of the mercury when the blades are moved to or toward theirlower position.

Another object of the invention is to provide in a switch of the generalcharacter defined, means for nance of arcs to an from the mercury afterit has been displaced to break the circuit since such arcs would causethe undesire production of mercury vapor and thereby provide arelatively good conductor across the terminals of the switch.

Anotherobject of the invention is to provide, in a non-arcing switch ofthe character described, generally improved mechanical structure.

Other objects and advantages will ap ear in the following descri tionand in the i ustrative embodiment o the invention in the accompanyingdrawings, in which:

Fig. 1 is an elevational view partly in section of a sin 1e pole switchembodying the invention,-t e switch bein shown by full and dotted linesin closed an open positions, res ectively;

ig. 2 is a sectional plan view taken on the line 22 of Fig. 1;

Fig. 3 is a fra entary sectional plan view taken on the line 33 of Fig.1;

Fig. 4 is an elevational view partly in section of a double pole switchembodying the invention; and

Figs. 5 and 6 are elevational views partly in section showingmodifications.

Referring to these drawings; the invention is capable of application tovarious types of switches in w ich there is a pivoted switch membermovable from a generally upright position to a generally dependingposition. The invention is also'capable of ap lication to any switchwherein the circuit 0 osing member is so movable as to cause asubstantial displacement of a liquid conductor, such as mercury, whichis contained in a member movable by the switch member. The invention hasbeen illustrated as embodied in the two' main types of switches,name'ly,the single 1e and double plole type but may be en; ield in various 0t ertypes of switches than those (preventing the mainte-' illustrated, forthe details of the switch structures shown may be varied in numerousparticulars and still embody the invention.

Referrin more particularly to Figs. 1, 2 and 3, t e invention asembodied in a switch of the single pole type, will first be described. Are resents the base of the switch, which is ormed of suitable insulatingmaterial, and secured to this base in laterally spaced relation arepairs of brackets I), each pair bein adapted to receive between them aswitch lade c, which is pivotally connected to the brackets at d. Theblades 0 are connected at their upper ends b a bar 6 of insulatingmaterial and, upon t e bar, a suitable handle (I is provided. Each blade0, when in close position, is received between a pair of jaws g and suchjaws are electricall connected together by a bar .5. The brac ets b, 6,form the terminals of the switch, which is thus of the single pole,double break type.

A block 6 of suitable insulating material, such as fibre or the like forexample, is supported by the blades 0. Pre erably, as shown, the blockis of rectangular shape, and of such size as to fill the space betweenblades 0, for the block, as will appear, is chambered to aflord a longand circuitous path and to obtain a path of the desired length, it isgenerally desired to make the block as large as possible. The block 6 isprovided with a plurality (three, as illustrated) of vertical passages 7therein, which are preferably circular in cross section, and extendfrom. the top of block 6 toward and closely adjacent t e lower endthereof. The block 6 is further provided near its lower end with athrough horizontal passage 8, also referably of circular cross section,whic passa e intersects all of the vertical passages.

oth ends of the passage 8 are closed by closely fitting screws 9,suitable material being applied to the threads thereof, if necessary, tosecure a ti ht and leak proof joint. The screws 9, as wi 1 ap ear,constitute electrodes and are electrica ly connected to the adjacentblades 0 in any suitable manner, as b integral studs 10 which passthrough the blades and are held thereto by nuts 11, thus serving also tosupport the block 6. Additional supporting connection between the block6 and blades 0 is afforded by screws 12 which pass through the bladesand thread into the block but do not enter any of the passagesdescribed.

The passages 7 are closed, and tightly sealed, by screws 13, which, ifnecessary to provide additional effective volume for the passages 7, maybe cupped out as indicated at 14. Each passage preferably, extendsslightly below the passage 8 to form a seat for, and receive, thecircular base 15' of a barrier member,the barrier ortion, indicated at16 extending upwar y a substantial distance into its passage 7 andparalleling the switch blades 0, to partition the passage. The bases 15preferably closely fit their seats to prevent leakage from the passa e8, and if necessary, may be addi tionafiy held to the block b screws 17.The passages 7 and 8 are supp ied, prior to the application of screws13, with mercury, as indicated at m, and the amount sup lied issuflicient to entirely fill passa e 8 an to fill passages 7 to a levelabove t e to s of the barriers 16, when the switch is 1n closedposition.

The particular form of single pole switch described is not necessarilyessential. For example, the terminals of the switch might consist of theleft hand bracket 6 and jaw g, the conductor 5 and the right hand 'aw 9being omitted and replaced by a con uctor 18 on the back of base A,which conductor would directly connect the right hand bracket 6 to theleft hand jaw g,- as shown in Figure 5.

Moreover, the invention is not necessarily confined to the use of thebrackets b as terminals of the switch and may equally well be used witha switch of the type having two jaws for each blade. Thus, as shown inFig. 6, the blade 0 pivoted at d to a bracket b, as described, isengageable with a second aw g as well as the jaw 9 described. The blade0 is therefore entirely disconnected from the circuit when in openposition. The member 6 may then be mounted centrall on blade 0 and arraned to overlie the latter bein mechanical y but not electrically connecteQ thereto b brackets 30. The electrodes 9 are connecte to separateblades 31, which are arranged one on each side of blade 0 and arepivoted at 32 to brackets 33 to swing about the same axis as blade 0.One bracket 33 is electrically connected by a strap 34 to jaw g and theother b a strap 35 to 'aw g.

Preferably, althoug not necessari y according to all features of theinvention, metallic members, as rods 19, are secured in the passages 7at points above the tops of barriers 16. The function of these rods willbe explained in the description of the operation of the switch.

The invention, as embodied in a double pole switch, will now bedescribed with reference to Fig. 4. Two blades 0, pivoted at d tobrackets ,b on base A and engageable with jaws g are provided, asheretofore described, but the aws g are not electrically connectedtogether as before. Two of the chambered members 6 are provided, eachsimilar in construction to that one described in connection with Fig. 1,and arran ed one above the other. One electrode 9 of t e upper member 6.is connected to the Ill ' throu h the other blade right hand blade 0but the a... c and is-insulated there rom by a bushing 20. Thelast-named electrode is connected to an auxiliary con-' ducting blade 21pivoted at 22 to a bracket 23 to swing about the same axis as blade 0and mechanically connected thereto as by 'a cross piece 24 ofinsulation. The l) 23 is electrically connected to the right hand 'aw.g, as by astrap 25 on the back of base A.

us, a divided circuit is formed between the right hand racket b and thecorresponding jaw g by t e right hand blade 0 and by the mercurycontained in the upper member 6. The construction described is generallyanalogous to that shown in'Fig. 1. Similarly the left hand electrode 9of the lower member 6 is electricall connected to the left hand blade 0while t e other electrode is connected to an auxiliary blade '26,pivoted similarly to blade 21 to a bracket 27, which is electricallyconnected to the left hand jaw g by a strap 28 on the back of base A.Thus, a divided circuit is formed between the left hand bracket b andthe corresponding jaw g by the left hand blade 0 and by the mercucontained in the lower member 6. The switch, illustrated in Fig. 1,afiords two paths for the current when it is in closed osition. One ofthese aths is of extremely ow, and almost ne liglble, resistance sinceit includes the meta lic blades 0, the jaws cross section.

and the metallic bar 5, all asusual, of amp e The other path,hereinafter with the path described it forms a divided circuit, is ofconsiderably higher resistance since the conductin' material is lar'ely"-mer- -=cury. Thus, when t e switch is inc osed posltlon, somecurrent constantly travels alon the shunt path but, due to therelativelyhig disengafed" from the resistance of this path, the amountof current flowin is very small,- the main path including b ades c andbar '5 affording practically a short circuit.

Upon an o ning of the switch, suflicient lades c from jaws g, thecircuit to disengage I is not immediately broken, but all the current isdiverted to the described shunt path. ath, although con-. siderablyhigher than t at of blades .0, is nevertheless not high enough toproduce a The resistance "of such drop of potential across the blades 0(even when carrying heavy currents) sufliciently lar to cause an arebetween the jawsg and bla es 0. At least no spark,'of suflicientintensity to be dangerous, occurs between the blades sand the aws whenthe former is litter. This resulti's attain by providing a large crosssectional area for the conducting path .through the mercury. For'cxamle, the resistance of the shunt path-may we be held to a few hundr'edthsor even a few thousandths of. an ohm racketso that even when heavycurrents, as for example, five hundred amperes, are carried, the drop ofvolts, notwit standing the fact that the retential may be held to a fewsistance of mercury is approximately sixty times that of copper.

The current. is carried by the shunt path only for a momentary intervaland, consequently, undue heating does not occur. The blades, whentdisenaged from jaws g, are swung downwardly into the dotted line position ina very short interval and the time durin which the current traverses theshunt path 1s so extremely short as. to be for all practical purposesnegligible. Upon a movement of t e blades 0 nito the dotted lineposition, the mercury and falls'away rom the electrodes 9 and barriers16. Thus the circuit through the so is displaced in member 6 shunt 'pathis broken out of contact with the surrounding atmos here and, sucharcing as occurs, cannot wor damage. The long cirelectrodes 9, the rods19 brother equivalent means, are (provided. Mercury vapor would beproduce side of a barrier 16 tolinto and t roug the mercury and backalon the other side of the barrier. The metal 10 rods 19, by theirinterposition between the top of barriers and that end of member 6,WhlCh contains the mercury when the switch is in open position, shortcircuits any such arcs and prevents them from? travelling beyond. intoand through the mercu The operation 0 the switches shown in only by anarc passin alon one Figs. 4 and 5, is analogous and will readily beunderstood from thexforegoing description. a 1

The inventionhas been disclosed herein for illustrative pur oses, inanembodiment, at present preferr and in ,detailed variations. It isrecognized, however, that modifications maybe made 'in the structuresherein disclosed, having for their object the use of the invention in aform differing specifi: cally, from that disclosed. It is therefore desired to have the 'sco of the invention defined by the ap ende claims,interpreted by the spirit of t e disclosure rather than by the letter'of the exact forms disclosed.

What I claim isa 1. In combination with a'switch, hav a movablecircuitcontrolling member an a devieia wit? which such meraibsr maygbs en to cose t 'e'circuit an ise to dgzn the circuit, a movable chaiiifired &nection between the first-named member and blades when said device whenthe member operable by movement of the firstan electrical connectionbetween said jaws,

named member and containi a' liquid conductor, and means cooperatm w thsuch conductor to establish ashunt e ectrical conformer engages thelatter.

2. In combination with a switch, havin a movable circuit controllingmember an a device withflwhich such member may be engaged to close thecircuit and disengaged to o n the circuit, a movable member opera le bymovement of 'the first-named member, a air of spaced electrodes therein,means e ectrically connecting one electrode to the first named memberand the other to said device when the former and latter are engaged, apassage provided in the second member, and a' iq filling such passageand electrically connect- 7 ing said electrodes when said device is envgaged by the first-named member, the latter being movable to displace.said conductor in the second member to break the connection between saidelectrodes and provide a circuitous non-conducting path from one to Ithe other..

3. In combination with' a switch, havin a movable circuit controllingmember and a device with which such member may be engaged to close thecircuit and disen .to open the circuit, a member movab e by thefirst-named member, a pair of spaced electrodes therein, means eectrically" connecting one electrode to the first-named member and theother to said device when the former and latter are engaged, a pas- 'eprovided in the second member; a liqd conductor partially fillingQBubhpassage and electrically connecting said electrodes when said. device isenga d by the firstnamed'member, the latter ing movable to uidconductorpartiallyw a chambered member movable \by the blades, and a liquidconductor in said member form-- ing an electrical connection between thethe latter are in generally u right position, said member being movab einto substantially inverted 'tion tobreak the last-named connection bg'displacement of said conductor.

6. A switch, comprising, two pivoted blades, Fa jaw engageable by eachblade, 'means electrically connecting said jaws, a member movable ondisengagement of said blades and jaws and provided with a circuitouspassage Q extending between. the blades, and a liquid conductorpartially filling said passage and formin an electrical connectionbetween the bla es when the latter are in generally uprightposition,said member being movable into substantially inverted position to" breakthe last-namedconnection by displacement of said conductor. r

7. In combination with a switch havi two pivoted knife" blades, a membercarri by and interposed between the blades, a passage extending acrosssaid member, electrodes .closing the ends of said assage and I eachconnected 'to the adjacent lade, a se- 1 ries of branch'passages leadingfrom the ,displace said conductor in the second memmaterial carried byand interposed between electrodes and rovide a circuitous non-conductingpath establish a shunt connection between said blades, the ivotsof saidblades forml jaw and blade when the, latter e'n ges the former, saidmember bein pivoted the terminals '0 the switch, a jaw for eachb ade,

5. A switch comprising, two

her to break the connection between said zithe blades,

om one to the other, and-- means in said passage tending to prevent themovab e on anopening of the blade to isplace said conductor and breaksaid connection.

aseries of holes extending from one end of the member toward the otherend thereof, a transverse passage intersecti all saidholes, an electrodein each end 0 said passage, a series of barriers each havi a circularbase seated in the baseof one 0 said holes and a' portion extendingacross .said passage'and into the holes to partition them, and mercurywithin said member and arranged to fill said assage and, fill said holesto a level above t e barriers when the blades are in substantiallyupright position. 9. A switch mechanism,-comprising, two acedcontacts,means providing two mule t1ple electrical connections betweensaid con tacts and including a member in eachoon riectionrmovable tointerru one of said connections bei low resistance and the other ofhigher resistance, the movable member in the connec-. tion of higherresistance having a. substan-- of relatively pt its connection,

aged first-named passage, barriers extending Ill tially air-tightchamber, and Ya liquid conductor in such chamber and forming a part ofthe high resistance connection.

10. A switch mechanism, comprising, two

5 's aced contacts, means providing two, multlple electrical connectionsbetween said contacts and including a member in each connection movableto interrupt its connection,

one of said connections being of relatively low resistance and the otherof higher resistance, the movable member in the connection of higherresistance having a substantially air-tight chamber, a liquid conductorin such ,chamber and forming part of the high resistance connection, andmechanical connections between said members to insure that the lowresistance connection will be interrupted before the connection ofhigher resistance and closed after the latter.

" HAROLD H. CLARK.

